Optical navigation device

ABSTRACT

An optical navigation device has a light-emitting unit, an optical navigation chip and a cover. The light-emitting unit provides a light to a surface of a displacement generating unit. The optical navigation chip has a sensing array, but excludes any optical lens for focusing a reflected light. The sensing array disposed opposite to the surface of the displacement generating unit receives the reflected light which the light provided by the light-emitting unit is reflected from the surface of the displacement generating unit. The cover has a first surface and a second surface, and an angle is formed between the cover and the optical navigation chip, to prevent another reflected light from the surface of the first surface of the cover from entering the sensing array. Particularly, the angle formed between the cover and the optical navigation chip is from 10 degrees to 15 degrees.

BACKGROUND

1. Technical Field

The instant disclosure relates to an optical navigation device; inparticular, to an optical navigation device without any optical lens forfocusing a reflected light.

2. Description of Related Art

Currently, the “holeless” design has been applied to lots of opticalnavigation devices to provide a great protection against dust. Generallyspeaking, these optical navigation devices have optical lenses toprevent the reflected light which the light is generated by the lightsource and reflected from the cover from entering the sensing array,wherein the reflected light from the cover entering the sensing arraycauses interferences that decrease the sensing accuracy. However, if thedistance between the light source and the image sensor decreases, itwill be hard to prevent the reflected light from the cover from enteringthe sensing array just by disposing the optical lens. Therefore, for the“holeless” optical navigation device without any optical lens, one otherspecific design should be required to prevent the reflected light whichthe light is generated by the light source and reflected from the coverfrom entering the sensing array.

SUMMARY

The instant disclosure provides an optical navigation device comprisinga light-emitting unit, an optical navigation chip and a cover. Thelight-emitting unit emits a light to a surface of a displacementgenerating unit. The optical navigation chip comprises a sensing array.The sensing array excludes any optical lens for focusing a reflectedlight, and is disposed opposite to the surface of the displacementgenerating unit to receive a reflected light which the light isreflected from the surface of the displacement generating unit. Thecover has a first surface and a second surface, wherein an angle isformed between the cover and the optical navigation chip to preventanother reflected light from the first surface of the cover fromentering the sensing array of the optical navigation chip.

In one embodiment of the instant disclosure, the angle formed betweenthe cover and the optical navigation chip is from 10 to 15 degrees.

In one embodiment of the instant disclosure, a distance between thecover and the sensing array of the optical navigation chip is less thana distance between the cover and the light-emitting unit.

To sum up, in the optical navigation device provided by the instantdisclosure, an angle is formed between the cover and the opticalnavigation chip. Thus, without expending the device volume, the otherreflected light from the first surface of the cover is efficientlyprevented from directly entering the sensing array of the opticalnavigation chip to cause interferences that will influence the sensingresult. Thereby, the optical navigation device provided by the instantdisclosure is dust-proof, can prevent the interferences and has a smallvolume.

For further understanding of the instant disclosure, reference is madeto the following detailed description illustrating the embodiments ofthe instant disclosure. The description is only for illustrating theinstant disclosure, not for limiting the scope of the claim.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements and in which:

FIG. 1A shows a schematic diagram of an optical navigation device of oneembodiment of the instant disclosure.

FIGS. 1B through 1D respectively show schematic diagrams of covers ofoptical navigation devices of different embodiments of the instantdisclosure.

FIG. 2 shows a schematic diagram of an optical navigation devicecomprising a cover and an optical navigation chip that have no angleformed therebetween.

FIGS. 3A and 3B respectively show energy distribution diagrams generatedby sensing arrays of optical navigation devices shown in FIG. 1A andFIG. 2.

FIG. 4 shows a schematic diagram of an optical navigation device ofanother embodiment of the instant disclosure.

FIG. 5 shows a schematic diagram of an optical navigation device ofstill another embodiment of the instant disclosure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The aforementioned illustrations and following detailed descriptions areexemplary for the purpose of further explaining the scope of the instantdisclosure. Other objectives and advantages related to the instantdisclosure will be illustrated in the subsequent descriptions andappended drawings.

It will be understood that, although the terms first, second, third, andthe like, may be used herein to describe various elements, but theseelements should not be limited by these terms. These terms are only todistinguish one element from another region or section discussed belowcould be termed a second element without departing from the teachings ofthe instant disclosure. As used herein, the term “and/or” includes anyand all combinations of one or more of the associated listed items.

[One Embodiment of an Optical Navigation Device]

FIG. 1A shows a schematic diagram of an optical navigation device of oneembodiment of the instant disclosure. As shown in FIG. 1A, the opticalnavigation device 1 comprises a light-emitting unit 10, an opticalnavigation chip 12 and a cover 14. The light-emitting unit 10 and theoptical navigation chip 12 are both disposed on a substrate B. Thelight-emitting unit 10 emits a light to the surface of a displacementgenerating unit (not shown). The optical navigation chip 12 comprises asensing array, and there is a distance D between the sensing array S andthe light-emitting unit 10. In addition, the sensing array S is disposedopposite to the surface of the displacement generating unit, to receivea reflected light which the light is generated by the light andreflected from the surface of the displacement generating unit. Itshould be noted that, in this embodiment, the sensing array S does nothave any optical lens (i.e. excludes any optical lens) for focusing theabove mentioned reflected light (i.e. the reflected light from thesurface of the displacement generating unit). The cover 14 preventsdusts from falling on the surface of the optical navigation chip 12. Thecover 14 has a first surface 141 and a second surface 142, and the cover14 has a thickness T.

Refer to FIGS. 1B through 1D, FIGS. 1B through 1D respectively showschematic diagrams of covers of optical navigation devices of differentembodiments of the instant disclosure. As shown in FIG. 1B, the cover 14b is plate-shaped and has a thickness. That is, the first surface 141 bof the cover 14 b only has one slope. For example, the thickness of thecover 14 b is from 0.5 mm to 1 mm. In another embodiment, the firstsurface 141 c is polygonal-curved, as shown in FIG. 1C. That is, thefirst surface 141 c of the cover 14 c has at least two different slopes,and thus is polygonal-curved. In still another embodiment, part of thefirst surface 141 d of the cover 14 d is curved and has its curvature,as shown in FIG. 1D. That is, part of the first surface 141 d of thecover 14 d is a curved surface. It should be noted that, the embodimentsshown in FIGS. 1B through 1D are only for illustrating eachimplementation related to the cover 14 of the optical navigation device1 in each embodiment, but not for restricting the instant disclosure.

It is worth mentioning that, in the optical navigation device 1 in thisembodiment, an angle θ is formed between the cover 14 and the opticalnavigation chip (i.e. the angle θ is the angle which the disposing planeof the optical navigation device 1 intercepts the disposing plane of thecover 14), to prevent another reflected light which the light isgenerated by the light-emitting unit 10 and reflected from the firstsurface 141 of the cover 14 from partly entering the sensing array S ofthe optical navigation chip 12. Thus, no interferences are induced toinfluence the sensing result.

Again refer to FIG. 1A, in this embodiment, the light-emitting unit 10emits the light to the surface of a displacement generating unit, tosense the displacement of the displacement generating unit. Thedisplacement generating unit can be a mouse roller, but it is notlimited herein. However, the optical navigation device 1 has a cover 14functioning as a dust-proof device, and thus, the light reaches thefirst surface 141 of the cover 14 before the light emitted by thelight-emitting unit 10 reaches the surface of the displacementgenerating unit. Therefore, the light will be partly reflected by thefirst surface 141 of the cover 14.

In conjunction with FIG. 1A and FIG. 2, FIG. 2 shows a schematic diagramof an optical navigation device comprising a cover and an opticalnavigation chip that have no angle formed therebetween. The differencebetween the optical navigation device 1 in this embodiment shown in FIG.1A and the optical navigation device 2 is that, the cover 24 and theoptical navigation chip 22 are disposed in parallel in the opticalnavigation device 2, as shown in FIG. 2. Once the light-emitting unit 20emits light toward the displacement generating unit (not shown), beforethe light reaches the surface of the displacement generating unit, thelight first reaches the first surface 241 of the cover 24. Thus, thelight is partly reflected from the first surface 241 of the cover 24,wherein part of the reflected light enters (i.e. is received by) thesensing array S. As described above, the sensing array S should receivethe reflected light from the surface of the displacement generatingunit, but not the reflected light from the first surface 241 of thecover 24. If the reflected light from the first surface 241 of the cover24 enters the sensing array S, interferences will be induced to decreasethe sensing accuracy.

To avoid the interferences, in the optical navigation device 1 of thisembodiment, an angle θ is formed between the cover 14 and the opticalnavigation chip 12. Even though the light first reaches the firstsurface 141 of the cover 14 before the light reaches the surface of thedisplacement generating unit, and partly reflected from the firstsurface 141 of the cover 14, the angle θ formed between the cover 14 andthe optical navigation chip 12 can be used to effectively prevent thereflected light from the first surface 141 of the cover 14 from enteringthe sensing array S. Thereby, the induced interferences that decreasethe sensing accuracy will be avoided.

In conjunction with FIG. 3A and FIG. 3B, FIGS. 3A and 3B respectivelyshow energy distribution diagrams generated by sensing arrays of opticalnavigation devices shown in FIG. 1A and FIG. 2. For the opticalnavigation device 2 having the cover 24 and the optical navigation chip22 disposed in parallel, according to the energy distribution diagramshown in FIG. 3B, part of the reflected light from the first surface 241of the cover 24 actually enters the sensing array S. On the contrary,for the optical navigation device 1 having an angle between the cover 14and the optical navigation chip 22, according to the energy distributiondiagram shown in FIG. 3A, none of the reflected light from the firstsurface 141 of the cover 14 enters the sensing array S. In other words,all of the reflected light from the first surface 141 of the cover 14goes outside between the sensing array S and the light-emitting unit 10,and then is reflected out. Thus, in this embodiment, the angle θ formedbetween the cover 14 and the optical navigation chip 12 can prevent thereflected light from the first surface 141 of the cover 14 from enteringthe sensing array S.

It should be noted that, in this embodiment, an angle θ is formedbetween the cover 14 and the optical navigation chip 12, so the distancebetween the cover 14 and the sensing array S is less than the distancebetween the cover 14 and the light-emitting unit 10. In one preferredembodiment, the angle θ formed between the cover 14 and the opticalnavigation chip 12 is from 10 to 15 degrees, and in another preferredembodiment, the angle θ formed between the cover 14 and the opticalnavigation chip 12 is 12.5 degrees. However, it is not limited herein.

It should be also noted that, in this embodiment, the light-emittingunit 10 is a coherent light source, and thus the light provided by thelight-emitting unit 10 is a coherent light. That is, the light providedby the light-emitting unit 10 has great temporal coherence and spatialcoherence, and has unitary color and uni-directivity. In one preferredembodiment, the optical navigation device 1 having no optical lens forfocusing the reflected light from the surface of the displacementgenerating unit, so that a divergence angle of the coherent light isfrom 16 to 18 degrees, such as 17 degrees, such that the reflected lightfrom the surface of the displacement generating unit will be effectivelysensed. As known, the divergence angle of a coherent light is related tothe amount of divergence of the coherent light. In this embodiment, thedivergence angle of a coherent light is defined as an angle within whichthe intensity of the coherent light is larger than or equal to 50% ofthe center intensity of the coherent light.

It is worth mentioning that, in this embodiment, the angle θ formedbetween the cover 14 and the optical navigation chip 12 is related tothe divergence angle of the coherent light. In details, the divergenceangle of the coherent light is related to its reflection andtransmittance in respect to a surface. Thus, the smaller the divergenceangle of the coherent light provided by the light-emitting unit 10 is,such as 16 degrees, the smaller the angle θ formed between the cover 14and the optical navigation chip 12 can be. On the contrary, the largerthe divergence angle of the coherent light provided by thelight-emitting unit 10 is, such as 18 degrees, the larger the angle θformed between the cover 14 and the optical navigation chip 12 is.

In addition, in this embodiment, the cover 14 of the optical navigationdevice is made of a light transmitting material, such as polycarbonate(PC), ABS resin, or the IR pass, to transmit the light, but it is notlimited herein. Moreover, in the optical navigation device 1 in thisembodiment, the sensing array S of the optical navigation chip 12 is acomplementary metal-oxide-semiconductor (CMOS) sensing array, but it isalso not limited herein.

[Another Embodiment of the Optical Navigation Device]

In the following embodiment, there are only parts different from thoseof the embodiment in FIG. 1A described, and the omitted parts areindicated to be identical to those of the embodiment in FIG. 1A. Inaddition, for an easy instruction, similar reference numbers or symbolsrefer to elements alike.

In conjunction with FIG. 4 and FIG. 5, FIG. 4 and FIG. 5 respectivelyshow schematic diagrams of optical navigation devices of otherembodiments of the instant disclosure. The difference between theoptical navigation device 4 in this embodiment and the opticalnavigation device 1 in the above described embodiment is that, in thisembodiment, the distance D′ between the sensing array S of the opticalnavigation chip 42 and the light-emitting unit 40 is adjustable.

Specifically, in this embodiment, in addition to the divergence angle ofthe coherent light provided by the light-emitting unit 40, the angle θ′formed between the cover 44 and the optical navigation chip 42 is alsorelated to the distance D′ between the sensing array S of the opticalnavigation chip 42 and the light-emitting unit 40.

In details, as shown in FIG. 4, if the distance D′ between the sensingarray S of the optical navigation chip 42 and the light-emitting unit 40increases, the possibility that the light reflected from the firstsurface 441 of the cover 44 enters the sensing array S will decrease.That is, the reflected light from the first surface 441 of the cover 44enters the sensing array S can be decreased by adjusting the distanceD′. Thus, even though the angle θ′ formed between the cover 44 and theoptical navigation chip 42 is small, such as 10 degrees or less than 10degrees, the light reflected from the first surface 441 of the cover 44can be prevented from entering the sensing array S via adjusting thedistance D′. On the contrary, if the distance D′ between the sensingarray S of the optical navigation chip 42 and the light-emitting unit 40decreases, the possibility that the reflected light from the firstsurface 441 of the cover 44 enters the sensing array S will increase.That is, the reflected light reflected from the first surface 441 of thecover 44 enters the sensing array S more. Thus, under this circumstance,the included angle θ′ formed between the cover 44 and the opticalnavigation chip 42 should increase, such as 15 degrees or larger than 15degrees, to prevent the reflected light from the first surface 441 ofthe cover 44 from entering the sensing array S.

As shown in FIG. 5, once the distance D′ between the sensing array S andthe light-emitting unit 40 increases to a critical distance Dc, thereflected light from the first surface 441 of the cover 44 cannot enterthe sensing array S. In other words, increasing the distance D′ betweenthe sensing array S and the light-emitting unit 40 to the criticaldistance Dc can prevent the reflected light from the first surface 441of the cover 44 from entering the sensing array S. Thereby, in thisembodiment, in order to prevent the reflected light from the firstsurface 441 of the cover 44 from entering the sensing array,selectively, the cover 44 and the optical navigation chip 42 can have anangle formed therebetween or be disposed in parallel (if the distance D′increases to the critical distance Dc).

To sum up, in the optical navigation device provided by the instantdisclosure, there is an angle formed between the cover and the opticalnavigation chip. Thus, without expending the device volume, anotherreflected light which the light is generated by the light source andrefelected from the first surface of the cover is efficiently preventedfrom directly entering the sensing array of the optical navigation chipto cause interferences that influence the sensing result. Thereby, theoptical navigation device provided by the instant disclosure isdust-proof, can prevent the interferences and has a small volume.

The descriptions illustrated supra set forth simply the preferredembodiments of the instant disclosure; however, the characteristics ofthe instant disclosure are by no means restricted thereto. All changes,alterations, or modifications conveniently considered by those skilledin the art are deemed to be encompassed within the scope of the instantdisclosure delineated by the following claims.

What is claimed is:
 1. An optical navigation device, comprising: alight-emitting unit, emitting a light to a surface of a displacementgenerating unit; an optical navigation chip, comprising: a sensingarray, excluding any optical lens for focusing a reflected light,disposed opposite to the surface of the displacement generating unit,receiving a reflected light which the light is reflected from thesurface of the displacement generating unit; and a cover, having aninner surface and an outer surface, wherein an angle is formed betweenthe cover and the optical navigation chip to direct another reflectedlight reflected by the inner surface of the cover away from entering thesensing array of the optical navigation chip.
 2. The optical navigationdevice according to claim 1, wherein the light-emitting unit is acoherent light source for providing a coherent light.
 3. The opticalnavigation device according to claim 2, wherein a divergence angle ofthe coherent light is from 16 to 18 degrees.
 4. The optical navigationdevice according to claim 1, wherein the angle formed between the coverand the optical navigation chip is from 10 to 15 degrees.
 5. The opticalnavigation device according to claim 1, wherein the angle between thecover and the optical navigation chip is 12.5 degrees.
 6. The opticalnavigation device according to claim 1, wherein a distance between thecover and the sensing array of the optical navigation chip is less thana distance between the cover and the light-emitting unit.
 7. The opticalnavigation device according to claim 1, wherein a distance between thelight-emitting unit and the sensing array of the optical navigation chipis adjustable.
 8. The optical navigation device according to claim 1,wherein the first surface of the cover is polygonal-curved and has atleast two different slopes.
 9. The optical navigation device accordingto claim 1, wherein part of the first surface of the cover is curved andhas its curvature.
 10. The optical navigation device according to claim1, wherein the cover is made of a light transmitting material.
 11. Theoptical navigation device according to claim 1, wherein the sensingarray of the optical navigation chip is a complementarymetal-oxide-semiconductor (CMOS) sensing array.
 12. The opticalnavigation device according to claim 1, wherein the cover isplate-shaped and a thickness of the cover is from 0.5 mm to 1 mm.